####### 7.2 - o modelo mais simples possivel

anim.m2 <- lm(log(brain)~log(body),data=Animals, 
              subset=!(log(Animals$body)>8&log(Animals$brain)<6))

anim.m0 <- lm(log(brain)~1, data=Animals, 
              subset=!(log(Animals$body)>8&log(Animals$brain)<6))

anova(anim.m0,anim.m2)

anova(anim.m2)

# anim.m0  o modelo cheio (nulo/total) de anim.m2

summary(anim.m0)
summary(anim.m2)
mean(log(Animals$brain[!(log(Animals$body)>8&log(Animals$brain)<6)]))
sd(log(Animals$brain[!(log(Animals$body)>8&log(Animals$brain)<6)]))

# a media da varivel Animals$brain(y)  o intercepto do modelo nulo.

anim.m0 <- update(anim.m2, .~. -log(body))